1. Field of the Invention
The present invention relates to a technique for recording dots on the surface of a recording medium with the aid of a dot-recording head, and more particularly to a technique for printing images up to the edges of printing paper without soiling the platen.
2. Description of the Related Art
Inkjet printers have recently become popular as computer output devices. Printing paper is supported on a platen opposite a print head and is transported on the platen such that various positions on the paper, from one end to another, are sequentially placed immediately underneath the head. A plurality of nozzles for ejecting ink drops are provided to the print head in the direction of advance of the printing paper. When the ink is ejected from the nozzles on the head, dots are sequentially recorded and images are printed on the printing paper.
To print images all the way to the edges of the printing paper with such a printer, it is necessary to put the printing paper in such a position that the edges of the printing paper are disposed underneath the print head (that is, on the platen). With such edge printing, however, the ink drops sometimes miss the edges of the printing paper (for which the drops have been originally intended) and end up depositing on the platen due to errors developing during the feeding of the printing paper, due to a shift in the impact locations of the ink drops, or the like. In such cases, the ink deposited on the platen may soil the printing paper subsequently transported over the platen.
An object of the present invention is to provide a technique that allows images to be printed up to the edges of printing paper while preventing ink drops from depositing on the platen.
Perfected in order to at least partially overcome the above-described shortcomings, the present invention envisages performing specific procedures for a dot-recording device designed to record dots on the surface of a print medium by ejecting ink drops while performing a main scan. The dot recording device comprises: a dot-recording head provided with a plurality of dot-forming element groups each of which comprises dot-forming elements for ejecting ink drops of a same color and occupies a different position in a direction of sub-scanning oriented across a direction of main scanning; a main scanning unit configured to perform main scanning by moving the dot-recording head and/or the print medium; a head driver configured to drive at least some of the dot-forming elements to form dots in the course of main scanning; a platen designed extends in a direction of main scanning while disposed opposite the dot-forming elements at least along part of a main scan pass, and that supports the print medium at a position opposite the dot-recording head; a sub-scanning unit configured to perform sub-scanning in between the main scans by moving the print medium in the direction of sub-scanning; and a control unit configured to control printing.
The platen comprises a plurality of slots that are extended in the direction of main scanning and are configured such that a width of the slot in the sub-scanning direction corresponds to not the entirety but part of a range of each dot-forming element group in the direction of sub-scanning. Such a dot-recording device allows each dot-forming element group to be used and dots to be recorded on the print medium above the slots. The dot-recording device makes it possible to print in color while preventing the platen from being soiled when ink drops miss the print medium.
Each of the dot-forming element groups may comprise a specific dot-forming element sub-group composed of specific dot-forming elements disposed within specific ranges commensurate with the width of the plurality of slots in the direction of sub-scanning. In this dot recording device, only the specific dot-forming element sub-groups are used to form dots at least in an edge portion not to have blank space in a first image print mode for printing images all the way to edges of the print medium without leaving blank spaces along an upper edge and/or a lower edge of the print medium.
Adopting this arrangement makes it possible to print images without blank spaces all the way to the upper or lower edge of a print medium by ejecting ink from dot-forming element groups disposed at different positions in a dot-recording device. As a result, color images can be printed without blank spaces all the way to the upper or lower edge of the print medium. In addition, the printing procedure in which edge portions are covered with printed images without blank spaces is carried out using specific dot-forming element sub-groups disposed opposite the slots, making it less likely that the upper surface of the platen will be soiled when ink drops miss the print medium. As used herein, the phrase xe2x80x9conly specific dot-forming element sub-groups are usedxe2x80x9d refers to the use of at least some of the dot-forming elements constituting specific dot-forming element sub-groups, without the use of dot-forming elements other than those belonging to the specific dot-forming element sub-groups.
It is preferable that the specific dot-forming element sub-groups in the plurality of dot-forming element groups have an identical number of dot forming elements. Adopting this arrangement allows printing to be performed in an efficient manner because each color is recorded on the print medium at the same pace in the first image print mode.
At least one of the specific dot-forming element sub-groups may preferably be located in a plurality of divided locations. The platen may also be provided with a plurality of the slots that are positioned opposite the specific dot-forming element sub-group at the plurality of divided locations.
The platen preferably comprises: upstream support portions each configured to support the print medium on upstream side of each slot in the direction of main scanning, and downstream support portions each configured to support the print medium on downstream side of each slot in the direction of main scanning. Adopting this arrangement allows the print medium to be supported on the upstream support or downstream support when the medium passes above the slots. The arrangement makes it less likely that the edge portions will be caught in the slots.
Each of the specific dot-forming element sub-groups may include at least one dot-forming element disposed within a specific range near a center of each dot-forming element group in the direction of sub-scanning. Adopting this arrangement allows higher-quality printed images to be obtained in the first image print mode for a dot-recording device in which the dot-forming elements disposed closer to the center in the direction of sub-scanning tend to better approximate design values in terms of performance than do the dot-forming elements disposed closer to the edges.
Only the specific dot-forming element sub-groups may be used to form all dots on the print medium in the first image print mode. Adopting this arrangement allows dots to be recorded by performing sub-scanning in accordance with a constant pattern from beginning to end.
It is preferable that a length of each slot in the direction of main scanning is greater than a width of a print medium having a specific standard size usable in the dot recording device. It is also preferable that ink drops are ejected from dot-forming elements selected from the specific dot-forming element sub-groups into an area near a side edge portion of the print medium supported on the platen to print images without leaving blank spaces in the side edge portion. Adopting this arrangement makes it possible to form dots without blank spaces in side edge portions and makes it less likely that an ink drop that has missed the print medium will soil the upper surface of the platen.
Dots in a middle portion located between the upper and lower edges of the print medium may be recorded in the first image print mode by using the specific dot-forming elements in the specific dot-forming element sub-groups and dot-forming elements other than the specific dot-forming element subgroups; and by performing the sub-scanning in greater increments than feed increments of sub-scanning in the edge portions. Adopting this arrangement makes it possible to print images faster than when dots are recorded with specific dot-forming element sub-groups alone.
For above described printing, it is preferable that a specific one of the slots disposed in an extreme upstream section in the direction of sub-scanning is located on downstream side in relation to a central position of a dot-forming element group facing the slot in the extreme upstream section in the direction of sub-scanning. It is also preferable that a specific one of the slots disposed in an extreme downstream section in the direction of sub-scanning is located on upstream side in relation to a central position of a dot-forming element group facing the slot in the extreme downstream section in the direction of sub-scanning. Adopting this arrangement makes it possible to narrow the range in which dots must be recorded on the print medium with specific dot-forming element sub-groups alone. Accordingly the printing can be performed in shorter period.
The platen may preferably further comprise a pair of lateral slots disposed at a distance substantially equal to a width of a specific sized print medium in the direction of main scanning within a range that allows ink drops to be deposited by the plurality of dot-forming elements in the direction of sub-scanning. The dot-recording device may preferably comprise a guide configured to position the print medium in the direction of main scanning such that the specific sized print medium can be supported on the platen and two side edges of the print medium can be kept at positions above openings of the lateral slots. In such an arrangement, it is preferable that ink drops are ejected from dot-forming elements selected from the specific dot-forming element sub-groups into an area near a side edge portion of the print medium supported on the platen to print images without leaving blank spaces in the side edge portion. Adopting this arrangement allows dots to be formed without blank spaces in the side edge portions of a print medium, and makes it less likely that the upper surface of the platen will be soiled.
It is preferable that dots are formed by using specific dot-forming elements and dot-forming elements other than the specific dot-forming elements in a second image print mode for printing images leaving blank spaces along the upper and lower edges of the print medium. Adopting this arrangement allows printing to be accelerated in a second image print mode for printing images without leaving blank spaces along the upper or lower edge.
The present invention can be implemented as the following embodiments.
(1) A dot-recording device, print control device, or printing device.
(2) A dot-recording method, print control method, or printing method.
(3) A computer program for operating the device or implementing the method.
(4) A storage medium containing computer programs for operating the device or implementing the method.
(5) A data signal transmitted by a carrier wave and designed to contain a computer program for operating the device or implementing the method.
These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with the accompanying drawings.